Alkyl esters of methylene citric acid.



UNITED STATES EQENT RUDOLPH BERENDES, OF ELBERFELD, GERMANY, ASSIGNOR TOFARBENFABRIKEN VORM. FRIEDR. BAYER & 00., OF ELBERFELD, GERMANY, ACORPORATION OF GERMANY.

ALKYL ESTERS OF METHYLENE CITRIC ACID.

Specification of Letters Patent.

Patented May 18,- 1909.

Application filed November 16, 1908. Serial No. 462,911.

To all whom it may concern:

Be it known that I, RUDOLPH BERENDES, doctor of philosophy, chemist,citizen of the German Empire, residing at Elberfeld, Kingdom of Prussia,Germany, have invented new new and useful Improvements in Alkyl Estersof Methylene Citric Acid, of which the following is a specification.

My invention relates to the manufacture and production of the hithertounknown alkyl esters of the methylene citric acid having most probablythe following general formula:

(ra ncoat o T co.o on cooa (R meaning an alkyl radical). The esters areobtained by esterification of the methylene citric acid or its salts orits derivatives.

The new esters are valuable therapeutic compounds. They are crystallinepowdess soluble with difficulty in water and soluble in alcohol, etherand chloroform. tasteless and non-irritant and are valuable remedies forinternal and external applicain the form of colorless and odorlessplates melting at 55? soluble with difficulty in water and easilysoluble in alcohol, ether and chloroform. It is split up by treatmentwith alkalies.

Example 2: 20 parts of pyridin are added while cooling to a mixture of24 parts of dichlorid of methylene citric acid, 17 parts of They are.

amyl alcohol and 100 arts of benzene. When the reaction is finis ed themixture is washed with acid to remove the yridin and then with a sodiumcarbonate so uti'on to remove the acid, the benzene solution is driedand the benzene distilled The amyl ester crystallizes from ligroin inthe shape of tasetless and odorless crystals meltingat 5255 C. It issoluble in alcohol, ether and chloroform, scarcely soluble in water andis split up by heatingit with caustic alkalies. w

The methylic ester is obtained in an analogous Way. It melts at 76 C.

Having now described my invention and in what manner the same is to beperformed,

what I claim as new and desire to secure by Letters Patent is 1. Theherein-described new alkyl esters of methylene citric acid, obtainableby esterification of methylene citric acid, and being white or stallinepowders; being soluble in ether, '9. cohol and chloroform and beingscarcely soluble in water, being split up by heating them with causticalkaliesyand exhibiting valuable therapeutic properties, substantiallyas hereinbefore described.

2. The herein described amyl ester of methylene citric acid, obtainableby esterification of methylene citric acid, and being a whitecrystalline owder meltin at 52 to 55. C. being soluble in ether, alcohoand chloroform and being scarcely soluble in water; be ing split up byheating it with caustic alkalies; and exhibiting valuable therapeuticproperties, substantially as hereinbefore described. y

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

RUDOLPH BERENDES. a. 5.

Witnesses OTTO KONIG, WALTER EJLMETSKAMP.

